Orthopaedic surgical instrument system and method for surgically preparing a patients bone

ABSTRACT

An orthopedic surgical instrument system for use in preparing a patient&#39;s bone is disclosed. The surgical instrument includes a cutting guide block configured to be secured to a surgically-prepared surface of the patient&#39;s bone, and a cutting tool to be used in conjunction with the cutting guide block to resect a section of the patient&#39;s bone. A method of performing an orthopedic surgery is also disclosed.

TECHNICAL FIELD

The present disclosure relates generally to orthopaedic surgicalinstruments and, more particularly, to surgical instruments used toprepare a patient's tibia or femur to receive an orthopaedic prostheticcomponent.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased or damaged natural joint is replaced by a prosthetic joint. Atypical knee prosthesis includes a tibial tray, a femoral component, anda polymer insert or bearing positioned between the tibial tray and thefemoral component. Over time, an implanted prosthesis can cause damageto the surrounding bone through component loosening, subsidence andosteolysis. A revision total knee arthroplasty may be used to replacethe original knee prosthesis and account for bone defects now present inthe patient. A primary or a revision knee prosthesis may include a coneimplant, which is a modular device used to correct for bone defects andprovide structural support for the other components of the prosthesis,such as, for example, a tibial tray or a femoral component.

SUMMARY

According to one aspect of the disclosure, an orthopaedic surgicalinstrument system is disclosed. The system comprises a cutting toolincluding a shank, a shaft extending distally from the shank, the shafthaving a plurality of cutting flutes defined at its distal end, and anouter sleeve coupled to the shaft. The system also comprises a cuttingguide block for use with the cutting tool. The cutting guide blockcomprises a superior surface, an inferior surface positioned oppositethe superior surface that defines an imaginary plane, and a slotextending through the superior surface and the inferior surface. Theslot defines a cutting guide that extends from a first end to a secondend that is sized to receive the cutting tool.

When the slot is viewed in a cross-sectional plane extendingperpendicular to the imaginary plane at each of a plurality of pointsbetween the first end and the second end, the slot has a central axisthat extends through the superior surface and the inferior surface, andan angle is defined between the central axis and the imaginary plane.The magnitude of the angle is non-constant between the first end of thecutting guide and the second end of the cutting guide such that thepitch of the cutting tool is adjusted as the cutting tool is moved alongthe cutting guide.

In some embodiments, the slot may be defined between a first inner wallextending from a first opening defined in the superior surface and asecond opening defined in the inferior surface, and a second inner wallextending from the first opening defined in the superior surface and thesecond opening defined in the inferior surface. The central axis may bepositioned between, and extend parallel to, portions of the first innerwall and the second inner wall when the slot is viewed in any of thecross-sectional planes extending perpendicular to the imaginary plane.

Additionally, in some embodiments, when the slot is viewed in any of thecross-sectional planes extending perpendicular to the imaginary plane, afirst width of the slot may be defined between a superior edge of thefirst inner wall and a superior edge of the second inner wall, and asecond width of the slot may be defined between an inferior edge of thefirst inner wall and an inferior edge of the second inner wall. Thesecond width of the slot may be less than the first width.

In some embodiments, when the slot is viewed in any of thecross-sectional planes extending perpendicular to the imaginary plane,the first inner wall may include a first section extending inwardly fromthe superior edge of the first inner wall to a transition surface and asecond section extending inwardly from the inferior edge of the firstinner wall to the transition surface. The first section may be curvedand the second section may define a straight imaginary line.

Additionally, in some embodiments, when the slot is viewed in any of thecross-sectional planes extending perpendicular to the imaginary plane,the second inner wall may include a first section extending inwardlyfrom the superior edge of the second inner wall to a transition surfaceand a second section extending inwardly from the inferior edge of thesecond inner wall to the transition surface. The first section of thesecond inner wall may be curved and the second section of the secondinner wall may define a straight imaginary line extending parallel tothe straight imaginary line defined by the second section of the firstinner wall. In some embodiments, the transition surfaces may define abeveled groove sized to engage the outer sleeve of the cutting tool.

In some embodiments, the slot may include a first slot section extendinganteriorly from the first end, a second slot section extending laterallyfrom the second end, and a third slot section connecting the first slotsection to the second slot section. Additionally, in some embodiments,the third slot section may include a first arced section connected tothe first slot section, a second arced section connected to the secondslot section, and a substantially straight section extending in amedial-lateral direction and connecting the first arced section and thesecond arced section.

In some embodiments, when the first arced section of the slot is viewedin a cross-sectional plane extending in a medial-lateral directionperpendicular to the imaginary plane, the angle defined between thecentral axis and the imaginary plane may have a first magnitude. Whenthe straight section of the slot is viewed in a cross-sectional planeextending in an anterior-posterior direction perpendicular to theimaginary plane, the angle defined between the central axis and theimaginary plane may have a second magnitude that is greater than thefirst magnitude. In some embodiments, the second magnitude may be lessthan 90 degrees.

In some embodiments, when the first slot section of the slot is viewedin a cross-sectional plane extending in a medial-lateral directionperpendicular to the imaginary plane, the angle defined between thecentral axis and the imaginary plane may have a magnitude ofapproximately 90 degrees.

In some embodiments, a pin guide may extend through the superior surfaceand the inferior surface. Additionally, in some embodiments, the pinguide may extend at a non-orthogonal angle relative to the imaginaryplane defined by the inferior surface.

In some embodiments, the cutting guide block may be formed from asemi-transparent polymeric material.

According to another aspect, the orthopaedic surgical instrument systemcomprises a cutting tool including a shank, a shaft extending distallyfrom the shank, the shaft having a plurality of cutting flutes definedat its distal end, and an outer sleeve pivotally coupled to the shaftsuch that the shaft and the shank are permitted to rotate relative tothe outer sleeve. The system may also comprise a cutting guide blockincluding a slot that defines a cutting guide sized to receive thecutting tool.

In some embodiments, the cutting tool may include at least one rollerbearing positioned between the shaft and the outer sleeve to pivotallycouple the outer sleeve to the shaft.

In some embodiments, the outer sleeve may include a cylindrical proximalsection that has a first diameter, a cylindrical distal section that hasa second diameter less than the first diameter, and a middle sectionconnecting the proximal section to the distal section. Additionally, insome embodiments, the cutting tool may include a flange that extendsoutwardly from the shaft, and the proximal section of the outer sleeveis engaged with the flange.

In some embodiments, the cutting guide block may include a first surfaceand a second surface positioned opposite the first surface, and the slotmay extend through the first surface and the second surface. The slotmay be partially defined by a pair of curved surfaces positioned betweenthe first surface and the second surface. The pair of curved surfacesmay be shaped to engage the middle section of the outer sleeve of thecutting tool.

In some embodiments, the cutting guide may extend from a first end to asecond end, and the slot may have a central axis. When the slot isviewed in cross-section, an angle may be defined between the centralaxis and an imaginary plane defined by an inferior surface of thecutting guide block. The magnitude of the angle may be non-constantbetween the first end of the cutting guide and the second end of thecutting guide.

According to another aspect, a method of performing an orthopaedicsurgery is disclosed. The method comprises positioning a cutting guideblock on an end of a patient's bone, inserting a cutting tool into aslot defined in the cutting guide block such that a cutting angle isdefined between the cutting tool and the proximal end of the patient'sbone, and advancing the cutting tool along the slot to resect a portionof the proximal end of the patient's bone. The shape of the slot causesthe cutting angle to change as the cutting tool advances along the slot.

In some embodiments, inserting the cutting tool into the slot mayinclude advancing an outer shell of the cutting tool into contact with atrack surface, and advancing the cutting tool along the slot may includemaintaining the outer shell into contact with the track surface androtating a shaft of the cutting tool relative to the outer shell toresect the portion of the proximal end of the patient's bone.

In some embodiments, the shape of the slot may cause the cutting angleof the cutting tool to decrease as the cutting tool moves from a firstend of the slot toward a medial side of the cutting guide block.

In some embodiments, the shaft of the cutting tool may be angled towarda medullary canal of the patient's bone as the cutting tool moves alonga section of the slot adjacent to the medial side of the cutting guideblock.

In some embodiments, the shape of the slot may cause the cutting angleof the cutting tool to increase as the cutting tool moves from thesection of the slot adjacent to the medial side of the cutting guideblock toward a lateral side of the cutting guide block.

Additionally, in some embodiments, the method may comprise inserting abone pin through a pin guide extending through the cutting guide blockinto the proximal end of the patient's bone at a non-orthogonal angle.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is an exploded perspective view of an orthopaedic prosthesis;

FIG. 2 is an exploded perspective view of an orthopaedic surgicalinstrument system for use in preparing a patient's bone to receive theorthopaedic prosthesis of FIG. 1;

FIG. 3 is a top plan view of a cutting guide block of the surgicalinstrument system of FIG. 2;

FIG. 4 is a bottom plan view of the cutting guide block of FIG. 3;

FIG. 5 is a side elevation view of the cutting guide block of FIGS. 4-5;

FIG. 6 is a cross-sectional elevation view taken along the line 6-6 inFIG. 3;

FIG. 7 is a cross-sectional elevation view taken along the line 7-7 inFIG. 3;

FIG. 8 is a cross-sectional elevation view taken along the line 8-8 inFIG. 3;

FIG. 9 is a cross-sectional elevation view taken along the line 9-9 inFIG. 3;

FIG. 10 is an exploded perspective view of a cutting tool of theorthopaedic surgical instrument system of FIG. 2;

FIG. 11 is a cross-sectional side elevation view of the cutting tool ofFIG. 10; and

FIGS. 12-16 are illustrations of a surgical procedure for using theorthopaedic surgical instrument system of FIG. 2 in preparing a proximalend of a patient's tibia to receive the orthopaedic prosthesis of FIG.1.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthe specification in reference to the orthopaedic implants and surgicalinstruments described herein as well as in reference to the patient'snatural anatomy. Such terms have well-understood meanings in both thestudy of anatomy and the field of orthopaedics. Use of such anatomicalreference terms in the written description and claims is intended to beconsistent with their well-understood meanings unless noted otherwise.While the disclosure below describes techniques and instrument system inreference to a patient's tibia, it should be appreciated that all of thesystems and techniques described below may be used to surgically prepareother bones, such as, for example, a distal end of a patient's femur.

Referring now to FIG. 1, an orthopaedic prosthesis 10 for use in apatient's tibia is shown. In the illustrative embodiment, theorthopaedic prosthesis 10 is configured for use in a primary or arevision total knee arthroplasty and includes a cone implant 12 and atibial tray 14 configured for implantation into a patient's tibia.Specifically, the cone implant 12 is configured to be secured to asurgically-prepared proximal end of a patient's tibia (see FIG. 16). Asdescribed in greater detail below, the surgical instrument system 70shown in FIG. 2 may be used to define a cavity in the proximal end of apatient's tibia that is sized and shaped to receive the cone implant 12.

As shown in FIG. 1, the cone implant 12 is formed from an implantablemetallic material such as, for example, stainless steel, cobaltchromium, titanium, and may be secured to the patient's tibia via use ofbone adhesive or other attachment means. The cone implant 12 is annularin shape, and includes a proximal rim surface 16, a distal rim surface18, and a sidewall 20 extending between the two rim surfaces 16, 18. Thesidewall 20 has a number of pores 22 defined therein, which areconfigured to permit bone ingrowth when the implant 12 is implanted in apatient's bone. In the illustrative embodiment, the sidewall 20 includesan anterior section 24 and a posterior section 26 that are substantiallystraight. The sections 24, 26 connect a medial section 28 and a lateralsection 30 of the sidewall 20. The sections 28, 30 are curved.

The sections 24, 26, 28, 30 of the sidewall 20 are tapered such that thegeometry of the implant 12 generally conforms to the geometry of thepatient's tibia. As a result, the implant 12 has a proximal maximummedial-lateral width that is greater than its distal maximummedial-lateral width of the cone implant 12. The implant 12illustratively also includes a pair of notches 36, 38 that are formed inthe medial and lateral sections 28, 30, respectively. The notches 36, 38are sized to accommodate the keels (not shown) protruding from thebottom of the tibial tray 14. It should be appreciated that in otherembodiments one or both of the notches 36, 38 may be omitted. In otherembodiments, the cone implant 12 may be stepped.

As shown in FIG. 1, the tibial tray 14 is configured to be positionedproximal of the cone implant 12. The tibial tray 14, like the coneimplant 12, may be secured to the patient's tibia via use of boneadhesive or other attachment means. The tibial tray 14 is formed from animplantable metallic material such as, for example, stainless steel,cobalt chromium, or titanium.

The tibial tray 14 includes a platform 50 having a top surface 52 and abottom surface 54. Illustratively, the top surface 52 is generallyplanar and, in some embodiments, may be highly polished. The tibial tray14 also includes a stem 56 extending downwardly from the bottom surfaceof the platform 50. A number of support buttresses 58 extend upwardlyfrom the top surface 52, and each buttress 58 is configured to engage atibial insert shaped to engage a femoral prosthetic component. A cavityor bore 60 is defined in one of the buttresses 58 and extends downwardlyinto the stem 56. The bore 60 is formed to receive a complimentary stemof the tibial insert.

Referring now to FIG. 2, an orthopaedic surgical instrument system 70for use in preparing a patient's bone to receive the orthopaedicprosthesis 10 is shown. In the illustrative embodiment, the instrumentsystem 70 includes a cutting guide block 72 and a cutting tool 74 foruse with the cutting guide block 72. The cutting guide block 72 includesa cutting guide slot 76 that is sized and shaped to receive the cuttingtool 74 and guide the cutting tool 74 to define a cavity that is sizedto receive an implant cone 12.

The cutting guide block 72 includes a superior surface 78, an inferiorsurface 80 positioned opposite the superior surface 78, and an outersidewall 82 extending between the two surfaces 78, 80. In theillustrative embodiment, the surfaces 78, 80 are substantially planarsurfaces that extend parallel to one another and define imaginary planes84, 86 (see FIG. 5), which will be discussed in greater detail below inreference to other features of the cutting guide block 72. As shown inFIG. 2, the cutting guide slot 76 extends through the surfaces 78, 80.

In the illustrative embodiment, the cutting guide block 72 is formedfrom a semi-transparent polymeric material, which permits a surgeon tomonitor the cut being made in the patient's bone while also reducing theglare that can be reflected by the cutting guide block 72 when it isplaced under bright surgical lights. Examples of suitablesemi-transparent polymeric materials are polyetherimide such as, forexample, Ultem or polycarbonate such as, for example, Lexan. It shouldbe appreciated that the cutting guide block 72 may be different sizes tofit different sizes of bone, allowing a surgeon to resect a cavity ofthe correct size in the tibia of the patient.

The cutting guide block 72 also includes a number of fixation pin guides88 that extend through both the surfaces 78, 80. Each pin guide 88 issized to receive a bone pin (not shown) to secure the cutting guideblock 72 to the patient's bone. In the illustrative embodiment, the pinguides 88 extend through the cutting guide block 72 at a non-orthogonal,or non-perpendicular, angle relative to the surfaces 78, 80.

As described above, the cutting guide slot 76 of the cutting guide block72 is sized and shaped to receive the cutting tool 74 and guide thecutting tool 74 to define a cavity that is sized to receive an implantcone 12. In the illustrative embodiment, the block 72 includes anopening 90 that is defined in the superior surface 78 and an opening 92that is defined in the inferior surface 80. A pair of inner walls 94, 96extends between the openings 90, 92 to define the cutting guide slot 76in the block 72. The slot 76 extends through the cutting guide block 72such that the block 72 is divided into an outer body 100, an inner body102, and a bridging section 104 positioned on the anterior side of theblock 72 that connects the bodies 100, 102. In the illustrativeembodiment, the outer body 100 includes the inner wall 94, while theinner body 102 includes the opposite inner wall 96.

As shown in FIGS. 3-4, the cutting guide slot 76 defines a guideway 106that extends from an end 108 located near the center of the block 72 toanother end 110 positioned adjacent the anterior side of the block 72.The guideway 106 defines a cutting path, which the cutting tool 74follows when resecting a patient's bone. In the illustrative embodiment,the guideway 106 is configured to change the pitch or angle of thecutting tool 74 when it is resecting the patient's bone such that thecutting tool 74 defines a tapered cavity corresponding to the taperedsidewall 20 of the cone implant 12. To do so, the pitch or angle of theguideway 106 relative to the imaginary plane 86 (and hence the inferiorsurface 80) is adjusted between the ends 108, 110 of the cutting guideslot 76, as shown in FIGS. 6-9 and described in greater detail below.

The guideway 106 is defined by a number of slot sections that vary inpitch relative to the imaginary plane 86. As shown in FIGS. 3-4, forexample, the guideway 106 includes a slot section 114 that extendsanteriorly from the end 108 of the cutting guide slot 76. In theillustrative embodiment, the section 114 defines a substantiallystraight cutting path. Another slot section 116 of the guideway 106extends laterally from the end 110 of the cutting guide slot 76. Theslot section 116, like the slot section 114, defines a substantiallystraight cutting path.

Another slot section 118 connects the sections 114, 116, as shown inFIGS. 3-4. In the illustrative embodiment, the slot section 118 includesa posterior section 120 that extends in a medial-lateral direction anddefines a substantially straight cutting path for the cutting tool 74.The slot section 118 also includes a pair of arced sections 122, 124that connect the posterior section 120 with the slot sections 114, 116,respectively. In the illustrative embodiment, the configuration of thearced section 122 mirrors the configuration of the arced section 124. Itshould be appreciated that the configuration of the guideway 106 may beadjusted based on the shape of the cone implant 12.

Referring now to FIGS. 6-9, the cutting guide slot 76 is shown in anumber of cross-sectional planes 130 extending perpendicular to thesurfaces 78, 80 (and hence planes 84, 86) of the cutting block 72 atvarious points along the slot 76. As described above, the slot 76 isdefined by a pair of inner walls 94, 96 extending from a superioropening 90 to an inferior opening 92. In the illustrative embodiment,the inner wall 94 extends from a superior edge 132 that partiallydefines the superior opening 90 to an inferior edge 134 that partiallydefines the inferior opening 92. The inner wall 94 includes a curvedsurface 136 that extends inwardly from the edge 132 to a transitionsurface 138 positioned between the surfaces 78, 80. Another surface 140extends from the transition surface 138 to the inferior edge 134. Asshown in FIGS. 6-9, the surface 140 defines a substantially straightline 142 when viewed in any of the cross-sectional planes 130.

In the illustrative embodiment, the inner wall 96 extends from asuperior edge 150 that partially defines the superior opening 90 to aninferior edge 152 that partially defines the inferior opening 92. Theinner wall 96 includes a curved surface 154 that extends inwardly fromthe edge 150 to a transition surface 156 positioned between the surfaces78, 80. Another surface 158 extends from the transition surface 156 tothe inferior edge 152. As shown in FIGS. 6-9, the surface 158 defines asubstantially straight line 160 when viewed in any of thecross-sectional planes 130. In the illustrative embodiment, the line 160defined by the surface 158 of the inner wall 96 extends parallel to theline 142 defined by the surface 140 of the inner wall 94.

As shown in each of FIGS. 6-9, a width 170 of the opening 90 is definedbetween the superior edges 132, 150 in each of the cross sectionalplanes 130. A width 172 of the opening 92 is also defined between theinferior edges 134, 152 in each of the cross sectional planes 130. Inthe illustrative embodiment, the width 170 is the superior width of thecutting guide slot 76, while the width 172 is the inferior width of thecutting guide slot 76. As shown in FIGS. 6-9, the superior width 170 isgreater than the inferior width 172 of the slot 76. As described ingreater detail below, the widths 170, 172 are sized to capture thecutting tool 74 and ensure that the cutting tool 74 does not extend intothe bone beyond a predetermined depth. It should be appreciated that thewidths 170, 172 may not be constant along the length of the guideway 106and may vary between each of the cross sectional planes 130 shown inFIGS. 6-9.

As shown in FIGS. 6-9, the cutting guide slot 76 has a central axis 174that is positioned between the inner walls 94, 96. In each of the crosssectional planes 130, the central axis 174 extends parallel to theinferior surfaces 140, 158 of the walls 94, 96, respectively. Asdescribed above, the pitch or angle of the guideway 106 relative to theimaginary plane 86 (and hence the inferior surface 80) is adjustedbetween the ends 108, 110 of the cutting guide slot 76. In theillustrative embodiment, the varying pitch or angle of the guideway 106is illustrated by the non-constant angles defined between the centralaxis 174 of the slot 76 and the imaginary plane 86 in the crosssectional planes 130 shown in FIGS. 6-9. For example, as shown in FIG.6, which is a cross section of the slot 76 taken in ananterior-posterior direction at the end 110 of the slot 76, an angle αis defined between the central axis 174 and the imaginary plane 86. Inthe illustrative embodiment, the angle α has a magnitude that isslightly less than 90 degrees such that the guideway 106 is pitchedinwardly (and hence away from the outer edge of the patient's bone whenthe block 72 is attached thereto). In that way, the pitch of theguideway 106 at that location corresponds to the taper of the coneimplant 12.

As shown in FIG. 7, which is a cross section of the slot 76 taken in amedial-lateral direction at the end 108 of the slot 76, an angle β isdefined between the central axis 174 and the imaginary plane 86. Becausethe end 108 is positioned near the center of the block 72 (and hence thecenter of the patient's bone when the block 72 is attached thereto), itis not necessary for the guideway 106 to be pitched at an angle, and, inthe illustrative embodiment, the angle β has a magnitude that isapproximately 90 degrees.

Similarly, as shown in FIG. 8, which is a cross section of the slot 76taken in an anterior-posterior direction in the posterior section 120 ofthe slot 76, an angle φ is defined between the central axis 174 and theimaginary plane 86. In the illustrative embodiment, the angle φ has amagnitude that is slightly less than 90 degrees such that the guideway106 is pitched inwardly (and hence away from the outer edge of thepatient's bone when the block 72 is attached thereto). In that way, thepitch of the guideway 106 at that location corresponds to the taper ofthe cone implant 12.

Referring now to FIG. 9, which is a cross section of the slot 76 takenin a medial-lateral direction in one of the arced sections 122 of theslot 76, an angle λ is defined between the central axis 174 and theimaginary plane 86. In the illustrative embodiment, the angle λ is lessthan 90 degrees such that the guideway 106 is pitched inwardly (andhence away from the outer edge of the patient's bone when the block 72is attached thereto). Because of the shape of the patient's tibia andthe taper of the cone implant 12, the angle λ has a magnitude that isless than the angles α, φ. In the illustrative embodiment, the magnitudeof the angle λ is in a range of 30 degrees to 70 degrees.

Returning to FIG. 2, the surgical instrument system 70 also includes acutting tool 74 that may be used with the cutting guide block 72. In theillustrative embodiment, the cutting tool 74 is a burring tool. Itshould be appreciated that in other embodiments the tool 74 may bereamer, surgical drill, cutting saw blade, or other cutting tool.Additionally, the system 70 may include multiple cutting tools ofdifferent lengths to resect different amounts from the patient's bone.Similarly, the system 70 may include cutting guide blocks 72 ofdifferent sizes to accommodate different sizes of patient bones.

The cutting tool 74 includes a shank 180 configured to be engaged by arotary power tool, and a shaft 182 extending distally from the shank180. The shaft 182 has a plurality of cutting flutes 184 defined at itsdistal end 186, which are configured to resect the patient's bone. Thecutting tool 74 further includes an outer sleeve 188 that is pivotallycoupled to the shaft 182 such that the shaft 182 and the shank 180 arepermitted to rotate about the tool's longitudinal axis 190 relative tothe sleeve 188, as described in greater detail below.

Referring now to FIG. 10, the shank 180 of the cutting tool 74 includesa flange 192 that extends outwardly from its distal end 194. The flange192 provides a stop for the outer sleeve 188 to keep the sleeve 188engaged with the shaft 182. The sleeve 188 includes a body 200 that hasa central passageway 202 defined therein, which is sized to receive theshaft 182. In the illustrative embodiment, the body 200 includes acylindrical proximal section 204 that engages the flange 192 and acylindrical distal section 206 that has a diameter 208 that is smallerthan the diameter 210 of the proximal section 204. A curved, beveledsection 212 connects the sections 204, 206.

As shown in FIG. 11, the cutting tool 74 also includes a pair of rollerbearings 214 that are positioned in the proximal section 204 of thesleeve 188. In the illustrative embodiment, the roller bearings 214 arepress-fit into the sleeve 188 and press-fit onto the shaft 182. Theroller bearings 214 are configured to permit relative rotation betweenthe outer sleeve 188 and the shaft 182 and the shank 180.

In the illustrative embodiment, the shank 180 and shaft 182 are formedas a single monolithic component from a stainless steel or othermetallic material. The sleeve 188 is also formed from a metallicmaterial such as, for example, stainless steel. It should be appreciatedthat in other embodiments other materials may be used. For example, thesleeve 188 may be formed from a plastic or polymeric material.

Referring now to FIGS. 12-16, an exemplary surgical procedure using thesystem 70 to surgically prepare a proximal end 220 of a patient's tibia222 to receive a cone implant 12 is shown. In the illustrativeembodiment, a reciprocating cutting saw or other cutting tool may beused to create a substantially planar surface 224 on the proximal end220, as shown in FIG. 12. A surgeon or other user may then place thecutting block 72 on the surface 224. When the block 72 is properlypositioned on the tibia 222, the surgeon may advance one or morefixation pins 226 through the fixation pin guides 88 in the block 72.Because the block 72 is formed from a semi-transparent material, thesurgeon may monitor the position of the pin tips by looking through theblock 72.

With the cutting guide block 72 positioned on the tibia 222, the surgeonmay advance the distal end 186 of the cutting tool 74 into the cuttingguide slot 76 and into contact with the patient's tibia 222. In theillustrative embodiment, the surgeon may first advance the cutting tool74 into the end 108 of the cutting guide slot 76. At that position, thedistal end 186 of the cutting tool 74 may extend outwardly from theinferior opening 92 of the slot 76 and into the intramedullary canal(not shown) of the tibia 222. The surgeon may continue to advance thecutting tool 74 into the guide slot 76 until the beveled section 212 ofthe cutting tool's outer sleeve 188 is engaged with the transitionsurfaces 138, 156 of the cutting block 72, which define a beveled groove230 sized to receive it (see FIG. 13). When the sleeve 188 is engagedwith the transition surfaces 138, 156, the cutting tool's longitudinalaxis 190 is coincident with the central axis 174 of the slot 76.

The surgeon may then activate a rotary power tool to cause the shank 180(and hence the cutting flutes 184) to rotate about the cutting tool'slongitudinal axis 190. Because the outer sleeve 188 is pivotally coupledto the shank 180 and the shaft 182, the outer sleeve 188 is isolatedfrom the power tool and does not rotate. While the cutting flutes 184are rotating and the outer sleeve 188 engaged with the transitionsurfaces 138, 156, the surgeon may advance the cutting tool 74anteriorly along the slot section 114 and into contact with thepatient's bone. When the surgeon reaches the end of the slot section114, the surgeon may continue to advance the cutting tool 74 along thearced section 122. As the cutting tool 74 is advanced along the section122, the pitch of the cutting tool 74 (and hence the cutting angle)changes. As shown in FIG. 13, when a cross section of the slot 76 takenin a medial-lateral direction with the cutting tool 74 is located in thearced section 122, the cutting tool 74 is pitched away from the outeredge 232 of the tibia 222 at the angle λ, which matches the taper of thecone implant 12 at that position relative to the patient's bone. Itshould be noted that the same angle λ is defined between the cuttingtool's longitudinal axis 190 and the resected surface 224.

As the cutting tool 74 is advanced along the slot 76, the pitch of thecutting tool 74 is changed. For example, as shown in FIG. 14, which is across section of the slot 76 taken in an anterior-posterior direction inthe posterior section 120 of the slot 76, the cutting tool 74 is pitchedat the angle φ, which matches the taper of the cone implant 12 at thatposition relative to the patient's bone. It should be noted that thesame angle φ is defined between the cutting tool's longitudinal axis 190and the resected surface 224.

In that way, as the cutting tool 74 is advanced along the slot 76, thepitch of the cutting tool 74 changes to match the corresponding changingtaper of the cone implant 12. In the illustrative embodiment, the pitch(and hence the cutting angle) first decreases, then increases, thendecreases again, before finally increasing back to slightly less than 90degrees as the cutting tool 74 is advanced from the end 108 to the end110 of the cutting guide slot 76.

As shown in FIG. 15, when the cutting tool 74 has completed its circuitaround the slot 76, a cavity 234 is defined in the surface 220 of thepatient's tibia 222, and the cutting tool 74 and the cutting guide block72 may be removed from the patient's tibia 222. The cavity 234 isdefined by a number of walls 236 that are shaped to match the outergeometry of the cone implant 12. As shown in FIG. 16, when the coneimplant 12 is positioned in the cavity 234, the cone implant 12 fitssnuggly against the walls 236.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

The invention claimed is:
 1. An orthopaedic surgical instrument systemconfigured to be used to prepare a proximal end of a patient's tibia toreceive an orthopaedic prosthetic component, the orthopaedic surgicalinstrument system comprising: a cutting tool including (i) a shank, (ii)a shaft extending distally from the shank, the shaft having a pluralityof cutting flutes defined at its distal end, and (iii) an outer sleevepivotally coupled to the shaft such that the shaft and the shank arepermitted to rotate relative to the outer sleeve, and a cutting guideblock sized and configured to be positioned on a surgically-prepared andsubstantially planar surface of the proximal end of the patient's tibia,the cutting guide block comprising: a superior substantially planarsurface, an inferior substantially planar surface positioned oppositethe superior surface, the superior and inferior surfaces extendingparallel to one another, the inferior surface being a tibial-contactingsurface and defining an imaginary plane, and a slot extending throughthe superior surface and the inferior surface, the slot defining acutting guide that is sized and shaped to receive the cutting tool, theslot extending from a first end located near the center of the cuttingguide block to a second end positioned adjacent an anterior side of thecutting guide block, wherein the slot divides the cutting guide blockinto an outer body, an inner body, and a bridging section positioned onthe anterior side of the cutting guide block that connects the outer andinner bodies, and when the slot is viewed in a cross-sectional planeextending perpendicular to the imaginary plane at each of a plurality ofpoints between the first end and the second end, (i) the slot has acentral axis that extends through the superior surface and the inferiorsurface, and (ii) an angle is defined between the central axis and theimaginary plane, the magnitude of the angle being non-constant betweenthe first end of the cutting guide and the second end of the cuttingguide, wherein the slot is defined between (i) a first inner wallextending between a first opening defined in the superior surface and asecond opening defined in the inferior surface, and (ii) a second innerwall extending between the first opening defined in the superior surfaceand the second opening defined in the inferior surface, wherein when theslot is viewed in any cross-sectional plane extending perpendicular tothe imaginary plane: (i) the central axis is positioned between, andextends parallel to, portions of the first inner wall and the secondinner wall, (ii) a first width of the slot is defined between a superioredge of the first inner wall and a superior edge of the second innerwall, (iii) a second width of the slot is defined between an inferioredge of the first inner wall and an inferior edge of the second innerwall, the second width of the slot being less than the first width, (iv)the first inner wall includes a first section extending inwardly fromthe superior edge of the first inner wall to a transition surface and asecond section extending inwardly from the inferior edge of the firstinner wall to the transition surface, the first section being curved andthe second section defining a straight imaginary line, (v) the secondinner wall includes a first section extending inwardly from the superioredge of the second inner wall to a transition surface and a secondsection extending inwardly from the inferior edge of the second innerwall to the transition surface, the first section of the second innerwall being curved and the second section of the second inner walldefining a straight imaginary line extending parallel to the straightimaginary line defined by the second section of the first inner wall,and (vi) the transition surfaces define a beveled groove sized to engagethe outer sleeve of the cutting tool, wherein the slot includes: a firstslot section extending anteriorly from the first end, a second slotsection extending laterally from the second end, and a third slotsection connecting the first slot section to the second slot section,wherein the third slot section includes (i) a first arced sectionconnected to the first slot section, (ii) a second arced sectionconnected to the second slot section, and (iii) a substantially straightsection extending in a medial-lateral direction and connecting the firstarced section and the second arced section, and wherein the cutting toolis configured to be advanced along the slot to define a cavity in thesurgically-prepared and substantially planar surface of the proximal endof the patient's tibia, the cavity being defined by a number of wallsthat are shaped to match the outer geometry of the orthopaedicprosthetic component.
 2. The orthopaedic surgical instrument system ofclaim 1, wherein: when the first arced section of the slot is viewed ina cross-sectional plane extending in a medial-lateral directionperpendicular to the imaginary plane, the angle defined between thecentral axis and the imaginary plane has a first magnitude, and when thestraight section of the slot is viewed in a cross-sectional planeextending in an anterior-posterior direction perpendicular to theimaginary plane, the angle defined between the central axis and theimaginary plane has a second magnitude greater than the first magnitude.3. The orthopaedic surgical instrument system of claim 2, wherein thesecond magnitude is less than 90 degrees.
 4. The orthopaedic surgicalinstrument system of claim 1, wherein when the first slot section of theslot is viewed in a cross-sectional plane extending in a medial-lateraldirection perpendicular to the imaginary plane, the angle definedbetween the central axis and the imaginary plane has a magnitude ofapproximately 90 degrees.
 5. The orthopaedic surgical instrument systemof claim 1, wherein a pin guide extends through the superior surface andthe inferior surface.
 6. The orthopaedic surgical instrument system ofclaim 5, wherein the pin guide extends at a non-orthogonal anglerelative to the imaginary plane defined by the inferior surface.
 7. Theorthopaedic surgical instrument system of claim 1, wherein the cuttingguide block is formed from a semi-transparent polymeric material.
 8. Theorthopaedic surgical instrument system of claim 1, wherein the cuttingtool includes at least one roller bearing positioned between the shaftand the outer sleeve to pivotally couple the outer sleeve to the shaft.9. The orthopaedic surgical instrument system of claim 1, wherein theouter sleeve includes (i) a cylindrical proximal section that has afirst diameter, (ii) a cylindrical distal section that has a seconddiameter less than the first diameter, and (iii) a middle sectionconnecting the proximal section to the distal section.
 10. Theorthopaedic surgical instrument system of claim 9, wherein the cuttingtool includes a flange that extends outwardly from the shaft, and theproximal section of the outer sleeve is engaged with the flange.